Effects of Water and Nitrogen Management on Nitrate Leaching Loss from Sands

Afield calibrated computer model was used to estimate the probable impact of different management prac-tices on nitrogen uptake and the loss of water and nitrate from the root zone of irrigated corn on sandy soil. The overall objective was to compare the contributions of nitrate to the ground water system, that may result from the wide range of existing management practices on ir-rigated sands in the central Great Plains. Three nitrogen sources, two nitrogen amounts, and a wide range of ir-rigation applications were simulated for wet, normal and dry growing seasons at North Platte, Nebraska. Control of irrigation amounts to minimize percolation and pro-per selection of nitrogen amount and source all significantly reduced nitrate leaching loss. However, model results indicate that it is impossible to reduce nitrate losses to near zero amounts and maintain present production levels. This would appear to have serious im-plications for ground-water quality in the future as ir-rigation continues to expand on sandy soils.